The effect of rotation on rapidly sheared homogeneous turbulence and passive scalar transport. Linear theory and direct numerical simulation
The effect of rotation on rapidly sheared homogeneous turbulence and passive scalar transport. Linear theory and direct numerical simulation
复制标题
旋转对快速剪切均匀湍流和被动标量传输的影响。
DOI：
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发表时间：
2005
影响因子：
3.7
通讯作者：
G. Brethouwer
中科院分区：
文献类型：
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作者：
G. Brethouwer
通过一系列不同旋转数的直接数值模拟，研究了旋转对均匀剪切湍流的影响。为了阐明旋转对湍流标量输运的影响，研究了在流中三个正交方向上具有平均梯度的被动标量场的演化。边界层近壁区的条件是用快速剪切来逼近的，因此可以与基于流动和标量输运线性化方程的快速畸变理论进行比较。计算了雷诺应力、压力-应变关系式和两点速度关系式，并对湍流结构进行了可视化。结果表明，旋转有很强的影响的时间发展的湍流动能，各向异性的流动和湍流结构。此外，旋转显着影响湍流标量输运。标量的输运速率和标量通量矢量的方向随旋转数的不同而变化较大，标量通量与雷诺应力张量主轴之间存在较强的一致性。湍流时间尺度和标量时间尺度的比值也受到旋转的影响。湍流单点统计和标量通量的线性理论的预测同意相当不错的直接数值模拟（DNS）的结果的基础上完全非线性控制方程。尽管如此，在一些情况下，观察到一些明显的和强烈的非线性效应，显着影响的湍流和标量输运的发展。
The effect of rotation on a homogeneous turbulent shear flow has been studied by means of a series of direct numerical simulations with different rotation numbers. The evolution of passive scalar fields with mean gradients in each of the three orthogonal directions in the flow was investigated in order to elucidate the effect of rotation on turbulent scalar transport. Conditions of the near-wall region of a boundary layer were approached by using a rapid shear and therefore, comparisons could be made with rapid distortion theory based on the linearized equations of the flow and scalar transport. Reynolds stresses, pressure–strain correlations and two-point velocity correlations were computed and turbulent structures were visualized. It is shown that rotation has a strong influence on the time development of the turbulent kinetic energy, the anisotropy of the flow and on the turbulent structures. Furthermore, rotation significantly affects turbulent scalar transport. The transport rate of the scalar and the direction of the scalar flux vector show large variations with different rotation numbers, and a strong alignment was observed between the scalar flux and the principal axes of the Reynolds stress tensor. The ratio of the turbulent and scalar time scales is influenced by rotation as well. The predictions of the linear theory of the turbulent one-point statistics and the scalar flux agreed fairly well with direct numerical simulation (DNS) results based on the full nonlinear governing equations. Nonetheless, some clear and strong nonlinear effects are observed in a couple of cases which significantly influence the development of the turbulence and scalar transport.